The Knee joint Flashcards
What are acute injuries to the knee caused by and where do they usually present to?
- sports
- falls
- elderly
- fracture
- tear/sprain of ligaments
- soft tissues
- cartilage
What causes acute swelling/ pain?
- atraumatic causes
- acute gout
- flare of Osteo-arthritis
- flare of RA
What causes chronic knee pain/ swelling?
- osteoarthritis
- bursitis
What can severe knee pain result in?
reduced mobility
poor sleep
reduced quality of life
How does chronic knee pain/swelling have to last for in order for it to be classified as chronic?
3-4 months to 1 year
What is not associated with the knee joint?
fibula
What type of joint is the knee joint?
hinge joint
synovial
What 3 bones are involved in the knee joint?
- distal femur
- proximal tibia
- patella
How many articulations do the 3 bones involved in the knee joint form?
3 articulations
What are the 3 articulations formed in the knee joint?
- 2 femorotibial - medial and lateral
- 1 femoropatellar
What is the most proximal part of the tibia like?
flat
What are the movements of the knee joint?
- extension/ flexion
- medial/lateral rotation - only a very small amount of rotation
Why do you lose knee flexion when the hip is extended?
due to the loss of tension on hamstrings
When can rotation occur?
when knee is flexed and collateral ligaments are relaxed
What happens when the knee joint approaches full extension?
the femur undergoes a few degrees of medial rotation on the tibia
this is also known as locking
What is locking?
joint approaching full extension and causing the femur to undergo a few degrees of medial rotation on the tibia
Is locking the knee stable or unstable and why is it so?
it is stable - as thigh muscles can relax
How is the knee unlocked?
By the popliteus muscle
What does the popliteus muscle do to the femur?
it laterally rotates the femur
Where and what is the popliteal fossa?
The space at the back of the knee
What runs through the popliteal fossa?
the popliteal artery
What are the medial and lateral femoral condyles?
expanded ends of the femur
What are the slight expansions of the proximal tibia?
medial and lateral tibial condyles
What is the flat surface of the tibia above the condyles known as?
tibial plateau - medial and lateral
What is the fit like of the tibial plateau with the rounded femoral condyles and what is the joint described as?
poor fit
incongruent
What is the tibial plateaux deepened by?
- 2 plates of fibrocartilage
- the menisci
What is stability and congruency like in extension?
most stable
very congruent
What is stability and congruency like in flexion?
unstable
least congruent
What are the menisci?
2 c shaped wedges of fibrocartilage
Where are the menisci thicker?
at the external margins
What are the functions of the menisci?
- increase joint congruency
- distribute weight evenly
- shock absorption
- assist in locking mechanism
What do the external edges of the menisci attach to?
fibrous capsule of the joint
What is the medial meniscus firmly attached to?
the tibial collateral ligament
What can cause meniscal tears?
sports or degenerative changes
What can cause pain or locking in meniscal tears?
displaced cartilage becoming trapped during knee movements
What is the treatment of meniscal tears?
repair or resection
What arthritis is damage of the meniscus associated with?
osetoarthritis
Why is the meniscus not very good at repairing itself?
as there is decreased blood supply
What are the different types of meniscal tears? (6)
- vertical
- transverse
- peripheral
- bucket handle
- parrot beak
- flap
What contribute to the stability of the knee?
ligaments
muscles - surrounding (most important part of the knee)
What are the ligaments inside the joint/ intra-articular ligaments?
anterior and posterior cruciate ligaments
What are the ligaments outside the joint/ extra articular ligaments?
fibular and tibial collateral ligaments
they work down on each side of joint
Where are the cruciate ligaments?
inside the joint capsule
how do the cruciate ligaments cross each in the centre of the knee?
obliquely
What does the posterior cruciate ligament attach to?
posterior intercondylar region of the tibia
Where does the posterior cruciate ligament travel?
supero-anteriorly to insert onto the medial femoral condyle
What does the anterior cruciate ligament attach to?
anterior intercondyle region of the tibia
How does the anterior cruciate ligament travel?
supero-posteriorly to attach to the lateral femoral condyle
Which is the stronger cruciate ligament?
Posterior cruciate ligament
What does the posterior cruciate ligament prevent?
posterior displacement of the tibia of the femur
hyperflexion
Which cruciate ligament is the main stabiliser of the flexed knee when weigh bearing?
posterior cruciate ligament
How can the posterior cruciate ligament be damaged?
When landing on the tibial tuberosity with the knee flexed - tibia slides backwards
What does the anterior cruciate ligament prevent?
anterior displacement of the tibia on the femur
hyperextension
How can the anterior cruciate ligament be damaged? (2)
when knee is hyperextended to force is applied anteriorly
Which cruciate ligament is more commonly injured?
anterior cruciate ligament
What is the tibial/medial collateral ligament?
a flat band attached to the medial meniscus
What does the tibial/medial collateral ligament prevent?
prevents abduction of the at the knee
What is the fibular/ lateral collateral ligament?
cord like band not attached to the lateral meniscus
What does the fibular/ lateral collateral ligament prevent?
prevents adduction of the leg at the knee
How does the lateral and medial collateral ligaments provide stability to the knee?
they prevent rotation during extension
What is a combined knee injury also known as?
the unhappy triad
What is a combined knee injury caused by?
excessive lateral twisting of the flexed knee
blow to the lateral side of the extended knee
What is torn in a combined knee injury?
tibial collateral ligament which is attached to the medial meniscus - which also tears
anterior cruciate ligament may also tear as it is taut during flexion (common when flexed knees are twisted)
What muscles are important in relation to the knee joint and act as the main stabilisers of the knee? (5)
- quadriceps
- hamstrings - posterior thigh
- sartorius
- gracillis
- illiotibial tract
What can compensate for ligament damage and avoid surgery?
building up quads through physio and exercise - cycling
What are two bursae you need to be aware of?
prepatellar bursa
suprapatellar bursa
What problems can occur with the bursae and who is more prone to getting them?
- prepatellar bursitis
- suprapatellar effusion
people who spend a lot of time on their knees
What are common bony fractures to the knee? (3)
Fractures to:
- patella
- tibia
- distal femur
What and where are the causes of the common bony fractures to the knee?
- trauma
- osteoporotic bone - low energy fractures
- peri-prosthetic - fractures around joint replacements
What are common meniscal tear causes?
- acute injury/ trauma
2. wear and tear
What are causes of ligamentous injuries to the knee?
- trauma
What injuries usually happen to the ligaments of the knee?
- tears and rupture
What are common dislocations?
- patella - more common in females
- whole knee joint - very uncommon
- acute injury/ trauma
What direction do patella dislocations occur?
laterally due to placement and alignment of the knee
What direction does the rectus femurs, vastus intermedius and vast us lateralis pull?
superolaterally
What are the rectus femurs, vast us intermedius and vastus lateralis counteracted by?
the horizontal pull of the vast us medial is
Why is patella dislocation more common in females?
ankle of the neck of the femur is different and therefore the angle of placement is bigger (Q angle)
What is the dislocation of the patella related to?
the alignment of the femur in relation to the tibia
What are examples of abnormal alignment of the femur in relation to the tibia?
- genu varum
2. genu algum
What is genu varum?
tibia is adducted wither respect to femur - bow leg
What is genu valgum?
Tibia abducted with respect to femur
What changes are apparent in osteoarthritis?
- osetophytes
- scleorosis - abnormal density of bone
- reduced joint space - very little meniscus
What does abnormal alignment of the knee lead to?
abnormal loading around the knee
What is a characteristic feature of a patellar fracture?
rough jagged ends
What shouldn’t you confuse a patellar fracture with?
bi-partite patellar - no jagged ends
What is a characteristic of a femoral fracture?
painful - shards of bone
How much force is required for a tibial plateau fracture?
- a lot
- can be subtle and can be easily missed
What tears in a complete knee dislocation?
cruciate ligaments - connecting the tibia to the femur
What would you worry about in complete knee dislocation?
damage to blood supply and nerve supply (popliteal artery and nerve)
